Combustion systems and methods for reducing combustion temperature

ABSTRACT

Embodiments disclosed herein are directed to combustion systems that include a mechanism or device for reducing combustion temperature. For example, in an embodiment, a combustion system may include a flame control assembly that may draw combusted fuel (e.g., flame produced during combustion) toward a structure that may absorb heat therefrom, thereby reducing combustion temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/015,683 filed on 23 Jun. 2014, the disclosure of which isincorporated herein, in its entirety, by this reference.

BACKGROUND

In some instances, reducing the combustion temperature may be desirable.For instance, combustion that occurs at a reduced temperature mayproduce less oxides of nitrogen (NOx) than the same or similarcombustion at a higher temperature (e.g., as compared with thecombustion temperature of a fuel without approaches for controllingcombustion temperature).

Generally, NOx is considered to be an air pollutant. For instance, NOxmay react to form ozone. As such, it may be preferable to reduce NOxproduction by devices and systems that combust fuel.

Accordingly, users and manufacturers of devices and systems that combustfuel continue to seek improvements to reduce NOx production by suchdevices.

SUMMARY

Embodiments disclosed herein are directed to combustion systems thatinclude a mechanism or device for reducing combustion temperature. Forexample, a combustion system may include a combustion control assembly.In some embodiments, the combustion control assembly may include acombustion controller that may control the device for reducingcombustion temperature. In some instances, the combustion controller andthe device for reducing combustion temperature may cooperate in a mannerthat attracts combusted fuel (e.g., flame produced during combustion)toward one or more structures that may absorb heat therefrom, therebyreducing combustion temperature of the flame.

One or more embodiments include a combustion system that has acombustion chamber including at least one chamber wall and a source ofcombustible fuel for producing a flame in the combustion chamber. Thecombustion system includes a flame control electrode assembly mounted tothe at least one chamber wall. More specifically, the flame controlelectrode assembly including a plurality of flame control electrodes.The flame control electrode assembly is configured to produce anelectric field that attracts the flame toward the chamber wall.

Embodiments are also directed to a method of reducing NOx producedduring combustion in a combustion chamber. The method includescombusting a fuel inside of the combustion chamber to produce a flamehaving a net positive charge or net negative charge. The method furtherincludes producing an electric field having a charge opposite to theflame charge. The electric field is positioned near at least one chamberwall of the combustion chamber. In addition, the method includesattracting the flame toward the at least one chamber wall andtransferring heat from the flame to the at least one chamber wall tothereby reduce a combustion temperature of the flame.

Embodiments also include a combustion system that includes a combustionchamber including at least one chamber wall, a source of combustiblefuel for producing a flame in the combustion chamber, and at least oneionizer. The ionizer is positioned and configured to ionize the fueland/or the produced flame. The combustion system also includes a flamecontrol electrode assembly mounted to the at least one chamber wall. Theflame control electrode assembly includes a plurality of flame controlelectrodes that are electrically insulated from each other. The flamecontrol electrode assembly is configured to produce an electric fieldthat attracts the flame toward the at least one chamber wall. Moreover,the combustion system includes a controller electrically coupled to theflame control electrode assembly. The controller is configured toregulate the electric field produced by the flame control electrodeassembly.

Features from any of the disclosed embodiments may be used incombination with one another, without limitation. In addition, otherfeatures and advantages of the present disclosure will become apparentto those of ordinary skill in the art through consideration of thefollowing detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate several embodiments, wherein identical referencenumerals refer to identical or similar elements or features in differentviews or embodiments shown in the drawings.

FIG. 1A is a cutaway plan view of a combustion system according to anembodiment of the invention;

FIG. 1B is a cutaway plan view of the combustion system of FIG. 1Aduring operation thereof according to an embodiment of the invention;

FIG. 1C is a cutaway partial isometric view of the combustion system ofFIG. 1A operating without an activated flame control electrode assembly;

FIG. 1D is a cutaway partial isometric view of the combustion system ofFIG. 1A operating with an activated flame control electrode assemblyaccording to an embodiment of the invention;

FIG. 2 is a partial isometric cutaway view of a flame control electrodeassembly mounted on a wall of a combustion chamber according to anembodiment of the invention;

FIG. 3 is a cross-sectional view of a flame control electrode assemblymounted on a wall of a combustion chamber according to an embodiment ofthe invention;

FIG. 4 is a cross-sectional view of a flame control electrode assemblymounted on a wall of a combustion chamber according to anotherembodiment of the invention;

FIG. 5 is a cross-sectional view of a flame control electrode assemblymounted on a wall of a combustion chamber according to yet anotherembodiment of the invention;

FIG. 6 is a cross-sectional view of a flame control electrode assemblymounted on a wall of a combustion chamber according to still anotherembodiment of the invention;

FIG. 7 is a cross-sectional view of a flame control electrode assemblymounted on a wall of a combustion chamber according to an additional oralternative embodiment of the invention; and

FIG. 8 is a flow diagram of a method for reducing NOx during combustionof a fuel according to an embodiment of the invention.

DETAILED DESCRIPTION

Embodiments disclosed herein are directed to combustion systems thatinclude a mechanism or device for reducing combustion temperature. Forexample, a combustion system may include a combustion control assemblythat may reduce temperature of combusted fuel (e.g., reduce flametemperature). The combustion control assembly, in some embodiments, mayinclude a combustion controller that may control the device for reducingcombustion temperature. In some instances, the combustion controller andthe device for reducing combustion temperature may cooperate in a mannerthat draws or attracts combusted fuel (e.g., flame produced duringcombustion) toward one or more structures that may absorb heattherefrom, thereby reducing combustion temperature.

In some embodiments, the device for reducing combustion temperature mayinclude one or more flame control electrode assemblies that may becontrolled and/or powered by the combustion controller. In the followingdetailed description, reference is made to the accompanying drawings,which form a part hereof. In the drawings, similar symbols typicallyidentify similar components, unless context dictates otherwise. Otherembodiments may be used and/or other changes may be made withoutdeparting from the spirit or scope of the disclosure.

FIG. 1A illustrates a combustion system 100 that may be deployed for anynumber of suitable objectives or uses, including but not limited toheating. For example, the combustion system 100 may include one or moresources of fuel and oxidizer, which may be combusted inside thecombustion chamber. The oxidizer may be supplied in the form ofcombustion air carrying oxygen. Specifically, in an embodiment, thecombustion system 100 may include a fuel line 110 that may supplycombustible fuel into a combustion chamber 120. In some embodiments,inside the combustion chamber 120, the fuel line 110 may terminate witha nozzle that may have suitable configuration for injecting the fuelinto the combustion chamber 120. Among other factors, the particularconfiguration of the fuel nozzle may be selected based on at least oneof the type of fuel, size of the fuel line, fuel pressure, configurationof the combustion chamber 120, etc. In any event, the fuel nozzle mayfacilitate spraying or otherwise injecting the fuel into the combustionchamber 120.

In some examples, the fuel line 110 may provide a premixed fuel that mayinclude an oxidizer such as air mixed with the fuel. For example, thefuel line 110 may inject a fuel-air mixture into the chamber, which maybe ignited or combusted inside the combustion chamber 120. Inalternative or additional embodiments, the combustion system 100 mayinclude a separate oxidizer line 130, which may supply an oxidizer thatmay be mixed with the fuel supplied by the fuel line 110. For instance,the oxidizer (e.g., air) supplied by the oxidizer line 130 may be mixedwith the fuel inside the combustion chamber 120, after the fuel isprovided into the combustion chamber 120. Alternatively, however, theoxidizer from the oxidizer line 130 may be mixed with the fuel from thefuel line 110 at another location (e.g., outside of the combustionchamber 120) and supplied into the combustion chamber by another line.Moreover, in some embodiments, the combustion chamber 120 may include anoxidizer that may facilitate ignition and/or combustion of the fuel. Inany case, the fuel supplied into the combustion chamber 120 may becombusted therein.

In an embodiment, the combustion system 100 also may include an exhaustor flue 140 that may facilitate removal of combusted gases that may beproduced during combustion. For example, the flue 140 may be positioneddistally from the fuel line 110 and/or from the nozzle (e.g., in thedirection of flow of the fuel), such that products formed during and/orafter combustion of the fuel may exit the combustion chamber 120 throughthe flue 140. In some embodiments, the flue 140 may be a passiveexhaust, which may allow exhaust gases to exit the combustion chamber120. Alternatively, the flue 140 may produce a negative pressure (atleast near the opening thereof in the combustion chamber 120), which mayactively draw the flame and/or exhaust gases produced during combustioninto the flue 140 and out of the combustion chamber 120.

In some embodiments, the combustion system 100 may include an igniterthat may ignite the fuel and oxidizer mixture inside the combustionchamber 120. It should be appreciated that any suitable igniter (e.g., aspark igniter) may be included in the combustion system 100, and thespecific igniter may vary from one embodiment to the next. Furthermore,in some instances, elevated temperature inside the combustion chamber120 may produce ignition and/or sustain ignition and combustion of thefuel mixture.

Generally, the combustion chamber 120 of the combustion system 100 mayhave any suitable size, shape, configuration, or combinations thereof.In the illustrated embodiment, the combustion chamber 120 has anapproximately rectangular shape defined by surrounding walls, such aschamber walls 150. The chamber walls 150 may include any number ofsuitable materials and/or components that may include refractory orotherwise heat-resistant materials (e.g., refractory blocks or firebrick), which may withstand the temperatures produced inside thecombustion chamber 120.

In some embodiments, the combustion system 100 may include a single fuelline 110. Alternatively, the combustion system 100 may include multiplefuel lines 110 (a centerline 10 provides an imaginary line of symmetryof the combustion chamber 120 and/or other components thereof). Hence,in some embodiments, the combustion system 100 may include multiple fuellines that may be similar to or the same as the fuel line 110, and whichmay be located on opposing sides of the combustion chamber 120.Furthermore, embodiments may include combustion chambers that may haveapproximately cylindrical, spherical, elliptical, or any other shapethat may be suitable for a particular application of the combustionsystem, for a particular fuel, and the like.

As mentioned above, in some embodiments, the combustion system 100 maybe a heater. For instance, the combustion system 100 may include one ormore heat exchangers 160 located inside the combustion chamber 120. Atleast a portion of the heat produced in the combustion chamber 120 (fromcombusting the fuel) may be transferred to the heat exchanger 160. Morespecifically, in some embodiments, the heat exchanger 160 may circulatefluid therethrough, and the fluid in the heat exchanger 160 may beheated as the fluid passes through the heat exchanger 160. For example,the heat exchanger 160 may be convectively heated inside the combustionchamber 120 and may transfer heat to the fluid circulating therethrough.

The heated fluid may be used to heat objects, substances, locations, orcombinations thereof. Additionally or alternatively, in someembodiments, the combustion system 100 may be in direct contact with oneor more objects or substances intended for heating and may transfer heatdirectly to such objects or substances (i.e., without a heat exchanger).In any case, the combustion system 100 may transfer at least a portionof the heat from the combustion chamber 120 to an intended or targetobject or substance.

The combustion system 100 further includes a device for reducingtemperature of combustion, such as a flame control electrode assembly170, which is described below in further detail. In an embodiment, theflame control electrode assembly 170 may be attached to and/or mountedon one or more of the chamber walls 150. For example, the flame controlelectrode assembly 170 may be located on the chamber walls 150 and maybe positioned distally from the outlet or nozzle of the fuel line 110.In one or more embodiments, the flame control electrode assembly 170 maybe positioned between the outlet or nozzle of the fuel line 110 and theflue 140.

In one or more embodiments, in operation, the flame control electrodeassembly 170 may attract the combusted fuel and oxidizer mixture (e.g.,the flame produce during combustion) as such combusted mixture extendsand/or moves away from the outlet of the fuel line 110. Moreover, theflame control electrode assembly 170 may transfer at least some heatfrom the combusted fuel to the chamber walls 150, thereby reducing acombustion temperature of the flame. As noted above, in some instances,reducing the temperature of the combusted fuel or flame may reduce NOxproduced thereby. Accordingly, the transferring heat from combusted fuelin the combustion chamber 120 to the flame control electrode assembly170 and/or to the chamber walls 150, may reduce NOx produced by thecombustion system 100.

In an embodiment, the fuel and/or oxidizer combusted in the combustionchamber 120 may be ionized. For example, the combustion system 100 mayinclude one or more ionizers, such as ionizers 180 a, 180 b that mayinject ions (i.e., electrically charged molecules) into the fuel and/oroxidizer, respectively, or may otherwise ionize the fuel and/oroxidizer. In some embodiments, ions may be injected into the oxidizer byarc discharge between a cathode and anode. Moreover, in some instances,an ionizer may inject ions directly into the flame (i.e., after ignitionof the fuel). For example, the ionizers 180 a, 180 b may be coronaelectrodes, such as a sharpened metallic electrode or a piece of ametallic saw blade.

The combustion system 100 further includes a combustion controller 190electrically coupled to the ionizers 180 a and/or 180 b. In someembodiments, the combustion controller 190 may regulate the flow of fueland/or oxidizer into the combustion chamber 120. The combustioncontroller 190 may also control the ionizers 180 a and/or 180 b and theflow of oxidizer and fuel in a manner that introduces a fuel mixture ofa desired or suitable ionization (i.e., a mixture that has a suitablenet positive or net negative charge) into the combustion chamber 120.

As shown in FIG. 1B, the flame control electrode assembly 170 mayattract the ionized fuel and oxidizer before combustion, duringcombustion, after combustion, or combinations thereof. For instance,FIG. 1B illustrates fuel and oxidizer mixture combusted to form a flame20, which may be attracted to the flame control electrode assembly 170,as the flame 20 advances from the fuel line 110 toward the flue 140. Insome embodiments, the combustion controller 190 also may be electricallycoupled to the flame control electrode assembly 170 and may controloperation thereof. For example, the combustion controller 190 may biasthe flame control and/or regulate electric field produced by the flamecontrol electrode assembly 170.

In some embodiments, the combustion controller 190 may direct the flamecontrol electrode assembly 170 to produce or generate a negativeelectric field. Alternatively, the combustion controller 190 may directthe flame control electrode assembly 170 to produce a positive electricfield. Furthermore, in an embodiment, the combustion controller 190 maydetermine whether to produce a negative or a positive electric field atleast in part based on the information about the net charge of the flame20. For example, the combustion controller 190 may include a specialpurpose computer or circuit or a general purpose computer, which may beprogrammed or otherwise configured to control or operate the flamecontrol electrode assembly 170.

In some instances, as mentioned above, the combustion controller 190 mayinject positively or negatively charged particles, such as ions, intothe fuel, oxidizer, flame, or combinations thereof. Hence, thecombustion controller 190 may use information about the injected ions todetermine the net charge of the flame. Additionally or alternatively,the combustion controller 190 may obtain information about the netcharge of the flame, which may be used to determine the charge for theelectric field. For example, the combustion controller 190 may firstdirect the flame control electrode assembly 170 to produce a negativeelectric field, and subsequently, a positive electric field, and maydetermine the net charge of the flame 20 based on the movement of theflame 20 in response to the produced electric fields. In any event, thecombustion controller 190 may direct the flame control electrodeassembly 170 in a manner that produces an electric field having that hasa charge that is opposite to the net charge of the flame 20.

In some embodiments, the combustion controller 190 may include a voltagesource. Alternatively, the combustion controller 190 may be electricallycoupled to a voltage source and may couple the voltage source to theflame control electrode assembly 170. In any event, as described belowin further detail, the flame control electrode assembly 170 may includemultiple flame control electrodes that may be biased to produce anelectric field that may have a charge that is opposite to the net chargeof the flame 20. Accordingly, the electric field may be at leastpartially controlled to manipulate movement of ions in the flame 20,which in some embodiment may attract the flame 20 to at least one of thechamber walls 150.

For example, the controlled electric field may create electrostaticforces (e.g., Coulombic body forces) within the flame 20 that may bemanipulated to control flame shape, combustion chemistry, heat transferthrough or away from a surface (e.g., the surface of the flame controlelectrode assembly 170), or combinations thereof, as desired or suitablefor one or more operating conditions. Also, in some embodiments, thecombustion controller 190 may be configured to apply a substantially orsuitable constant voltage or time-varying voltage to one or more of theflame control electrodes in the flame control electrode assembly 170 andmay generate substantially or suitable constant or time-varying electricfield strength (e.g., the strength of the electric field may be suitableto attract and/or more the flame toward the flame control electrodeassembly 170).

In an embodiment, the combustion controller 190 and the flame controlelectrode assembly 170 may be collectively configured to varyapplication of the electric field to the flame 20 at selected timesand/or locations. In alternative or additional embodiments, thecombustion controller 190 may be configured to change a polarity of thevoltage applied to the one or more of the flame control electrodes inthe flame control electrode assembly 170. Also, the combustioncontroller 190 may be configured to vary a magnitude or frequency of avoltage applied to one or more of the flame control electrodes in theflame control electrode assembly 170 at selected times and/or locations.

In an embodiment, the combustion controller 190 and the flame controlelectrode assembly 170 may cause a response in the flame 20. Forinstance, by controlling timing, direction, strength, location, waveform, frequency spectrum of the electric field, or combinations thereof,the combustion controller 190 and flame control electrode assembly 170may cooperate to influence combustion characteristics of the flame 20,such as the shape of the flame 20, position of the flame 20 within thecombustion chamber 120 (e.g., position relative to the wall chamber150), heat transfer from the flame 20, or combinations thereof.

Additionally or alternatively, causing a response in the flame 20 mayinclude causing increased mixing of fuel and oxidizer in the flame 20.In an embodiment, causing the increased mixing of fuel and oxidizer mayincrease a rate of combustion. In some embodiments, causing theincreased mixing of fuel and oxidizer may increase fuel and oxidizercontact in the flame 20. Moreover, causing the increased mixing of fueland oxidizer may decrease a flame temperature.

In an embodiment, causing the increased mixing of fuel and oxidizer maydecrease an evolution of oxides of nitrogen (“NOx”) by the flame 20. Insome instances, causing the increased mixing of fuel and oxidizer maydecrease an evolution of carbon monoxide (“CO”) by the flame 20.Furthermore, causing the increased mixing of fuel and oxidizer mayincrease flame stability and/or decrease a chance of flame blow-out.Also, causing the increased mixing of fuel and oxidizer may increaseflame emissivity. In alternative or additional embodiments, causing theincreased mixing of fuel and oxidizer may decrease flame size for agiven fuel flow rate.

As noted above, attracting fuel mixture and/or the 20 to the flamecontrol electrode assembly 170 may reduce the combustion temperatureinside the combustion chamber 120, thereby reducing NOx produced by thecombustion system 100. More specifically, in some embodiments, the flamecontrol electrode assembly 170 and/or one or more of the chamber walls150 may absorb and/or transfer heat away from the flame 20, therebyreducing temperature thereof. In turn, in some embodiments, reducingcombustion temperature of the flame 20 may reduce the amount NOxproduced during combustion.

In some embodiments, the flame control electrode assembly 170 and/or thechamber walls 150 may be in thermal communication with a coolingelement, such as a heat sink, a heat exchanger, a similar coolingstructure, or combinations thereof, which may transfer the heat awayfrom the flame control electrode assembly 170 and chamber walls 150,thereby reducing temperature thereof. Hence, attracting the flame 20 tothe flame control electrode assembly 170 and/or to the chamber walls 150may transfer heat away from the flame 20 to the flame control electrodeassembly 170 and/or to the chamber walls 150 (i.e., since the flamecontrol electrode assembly 170 and/or to the chamber walls 150 may becontinuously or intermittently cooled by a cooling element). It shouldbe appreciated that the flame control electrodes of the flame controlelectrode assembly 170 may include thermally conductive material, whichmay transfer heat from the flame (i.e., the flame control electrodes ofthe flame control electrode assembly 170 may form a heat sink).

In one or more embodiments, the combustion system 100 may include a heatexchanger that may circulate a cooling fluid therethrough, which maycool the flame control electrode assembly 170. As noted above, in someinstances, the cooling element may be thermally coupled to the flamecontrol electrode assembly 170. Alternatively or additionally, thecooling structure may be integrated within the flame control electrodeassembly 170 (e.g., the flame control electrode assembly 170 may includefluid channels for circulating a cooling fluid through the flame controlelectrode assembly 170). Such fluid may cool the flame control electrodeassembly 170 and produce a temperature differential between the flamecontrol electrode assembly 170 and the flame 20 to facilitate heattransfer therebetween. In any event, the heat from the flame 20 may betransferred to the flame control electrode assembly 170 and/or thechamber walls 150 to cool the flame 20 and reduce NOx produced duringcombustion. In some embodiments, the heat removed from the flameelectrode assembly 170 (e.g., heat transferred to the cooling fluid) maybe used to heat one or more elements or components.

FIGS. 1C and 1D illustrate an enlarged view of the flame 20 before andafter activation of the flame control electrode assembly 170. Morespecifically, FIG. 1C shows the flame 20 during combustion inside thecombustion chamber, but before activation of the flame control electrodeassembly 170. As illustrated in FIG. 1D, after the flame controlelectrode assembly 170 is activated, the flame control electrodeassembly 170 attracts the flame 20 to the flame control electrodeassembly 170 and to the chamber walls 150. As described above, heat fromthe flame 20 may be transferred to the chamber walls 150 and/or to theflame control electrode assembly 170.

For example, the flame 20 may convectively transfer heat to the chamberwalls 150 and/or to the flame control electrode assembly 170.Additionally or alternatively, the flame 20 may contact the chamberwalls 150 and/or the flame control electrode assembly 170. Hence, in oneor more embodiments, the flame 20 may conductively transfer heattherefrom to the chamber walls 150 and/or to the flame control electrodeassembly 170. In any case, in one or more embodiments, the flame 20 maytransfer heat to the chamber walls 150 and/or to the flame controlelectrode assembly 170, which may reduce combustion temperature of theflame 20.

Generally, the flame control electrodes of the flame control electrodeassembly 170 may have any number of suitable configurations andarrangements. For example, FIG. 2 illustrates a flame control electrodeassembly 170 a that includes flame control electrodes 200 a spaced fromeach other. Except as otherwise described herein, the flame controlelectrode assembly 170 a and its materials, elements, and components maybe similar to or the same as the flame control electrode assembly 170(FIGS. 1A-1B) and its corresponding materials, elements, and components.In some embodiments, similar to the flame control electrode assembly 170(FIGS. 1A-1B), the flame control electrode assembly 170 a may beelectrically coupled to the combustion controller 190, which may controloperation of the flame control electrode assembly 170 a (e.g., in amanner described above).

In one or more embodiments, the flame control electrodes 200 a may be atleast partially or entirely encapsulated in one or more insulationelements, such as in an insulation element 210 a. For instance, theflame control electrodes 200 a may be overmolded in glass, which mayform the insulation element 210 a when cooled. Additionally oralternatively, the flame control electrodes 200 a may be enclosed orencapsulated between two glass sheets, which may be fused together (asdescribed below in more detail) to form a substantially unitary and/ormonolithic insulation element.

The flame control electrodes 200 a may include any suitable electricallyconductive material that may vary from one embodiment to the next. Insome examples, the flame control electrodes 200 a may include any of thefollowing materials: copper, aluminum, alloys thereof, similar materials(e.g., electrically conductive materials), or combinations thereof.Alternatively or additionally, in some embodiments, the flame controlelectrodes 200 a may include refractory materials, such as molybdenum,tungsten, niobium, tantalum, rhenium, alloys of the foregoing,combinations thereof, or any other suitable material.

In some embodiments, the flame control electrodes 200 a may have anapproximately circular cross-section. For example, the flame controlelectrodes 200 a may be wires of a suitable wire gauge. Also, asdescribed in further detail below, the flame control electrodes 200 amay have any number of suitable cross-sections, which may vary from oneembodiment to the next.

The insulation element 210 a may include any suitable material.Generally, the insulation element 210 a may include materials suitablefor electrically insulating the flame control electrodes 200 a (e.g.,sufficient insulation to prevent shorting the flame control electrodes200 a by charged particles of the flame). Furthermore, materials thatform the insulation element 210 a also may withstand temperatures insidethe combustion chamber and protect the flame control electrodes 200 afrom such temperatures (e.g., thermally insulating the flame controlelectrodes 200 a to prevent damage thereof). For example, the insulationelement 210 a may include quartz glass. It should be appreciated,however, that the insulation element 210 a may include other suitablematerials, such as other ceramics and the like.

The insulation element 210 a also may encapsulate connections from thecombustion controller 190 to the flame control electrodes 200 a. Forexample, the flame control electrodes 200 a may be wired or otherwiseconnected together in a manner that allows the combustion controller 190to connect to the flame control electrode assembly 170 a at a singlelocation. In some examples, alternating flame control electrodes of theflame control electrodes 200 a may be electrically coupled in parallelto provide two opposite polarity connection locations for the combustioncontroller 190.

Alternatively, the combustion controller 190 may couple to the flamecontrol electrodes 200 a at multiple locations. As such, the combustioncontroller 190 and the flame control electrode assembly 170 a maygenerate multiple electric fields that may vary from one location toanother or may be the same. For example, the flame control electrodeassembly 170 a may generate a stronger electric field at one or morelocations that are farther away from the fuel outlet or nozzle than atlocations closer to the fuel outlet, or vice versa. It should be alsoappreciated that the electric field generated by the flame controlelectrode assembly 170 a and combustion controller 190 may continuouslyvary along the length (i.e., in a direction away from the fuel supply)of the flame control electrode assembly 170 a and chamber walls 150 a.

The electric field also may vary based on the flame or combustioncharacteristics. In some embodiments, the combustion controller 190 mayautomatically regulate or adjust the electric field generated by theflame control electrode assembly 170 a and combustion controller 190 ina manner that attracts the flame to the flame control electrode assembly170 a. In any case, the flame control electrode assembly 170 a mayattract the flame thereto and, thus, to the chamber walls, such aschamber wall 150 a.

The flame control electrode assembly 170 a may be mounted on the chamberwall 150 a in any number of suitable ways. For example, the flamecontrol electrode assembly 170 a may be fastened, adhered, or otherwisesecured to or integrated with the chamber wall 150 a. As describedabove, in one or more embodiments, a cooling device, such as a heatexchanger may be in thermal communication with the flame controlelectrode assembly 170 a. In particular, in some embodiments, a coolingdevice may be located between the flame control electrode assembly 170 aand the chamber wall 150 a. Alternatively, the cooling device may beincorporated into the chamber wall 150 a and/or into the flame controlelectrode assembly 170 a (e.g., cooling lines may be included in thechamber wall 150 a and/or in the flame control electrode assembly 170 aat suitable locations).

Insulation elements may have a sheet- or plate-like shape and may secureand insulate flame control electrodes therebetween. Hence, for example,the flame control electrode assembly may include two or more fused glasssheets or elements that may at least partially insulate one or moreflame control electrodes of the flame control electrode assembly. FIG.3, for example, illustrates a flame control electrode assembly 170 bthat includes insulation elements 210 b and 210 b′ that encapsulateflame control electrodes 200 b. Except as otherwise described herein,the flame control electrode assembly 170 b and its materials, elements,and components may be similar to or the same as any of the flame controlelectrode assemblies 170, 170 a (FIGS. 1A-2) and their correspondingmaterials, elements, and components. In some embodiments, the insulationelements 210 b and 210 b′ may comprise similar or the same material,such as quartz glass.

Alternatively, the insulation elements 210 b and the 210 b′ may includedissimilar materials. For instance, the insulation element 210 b mayinclude refractory ceramic, while the insulation elements 210 b′ mayinclude glass. Moreover, while in some embodiments, the insulationelements 210 b and 210 b′ may be fused together, in other embodiments,the insulation elements 210 b and 210 b′ may be bonded, adhered,fastened, or otherwise secured together. Also, in some examples, (e.g.,when the insulation elements 210 b and 210 b′ are bonded or otherwisesecured together), the materials included in the insulation elements 210b may have similar or the same coefficient of thermal expansion as thematerials included in the insulation elements 210 b′. Embodiments alsomay include the insulation elements 210 b and 210 b′ that have differentcoefficients of thermal expansion (e.g., bonding material between theinsulation elements 210 b and 210 b′ may accommodate different rates ofthermal expansion of the insulation elements 210 b, 210 b′, flamecontrol electrodes 200 b, and combinations thereof).

In an embodiment, the insulation elements 210 b and 210 b′ may be firstsecured together (with the flame control electrodes 200 b sandwichedtherebetween) and then mounted or secured on the chamber wall 150 b. Inalternative or additional embodiments, the insulation element 210 b maybe first mounted on the chamber wall 150 b and, subsequently, theinsulation element 210 b′ may be secured to the insulation element 210 band to the chamber wall 150 b. Also, in some instances, the flamecontrol electrodes 200 b may be secured to or at least partially withinthe insulation element 210 b before securing the insulation element 210b to the insulation element 210 b and/or to the chamber wall 150 b.Optionally, the insulation element 210 b may be first secured to thechamber wall 150 b and thereafter, the flame control electrodes 200 bmay be secured to and/or within the insulation element 210 b.

Furthermore, the flame control electrodes may be first secured to a walland subsequently insulated and/or at least partially enclosed orencapsulated by one or more insulation elements. FIG. 4, for example,illustrates a flame control electrode assembly 170 c that includes flamecontrol electrodes 200 c positioned near or on the chamber wall 150 c.Except as otherwise described herein, the flame control electrodeassembly 170 c and its materials, elements, and components may besimilar to or the same as any of the flame control electrode assemblies170, 170 a, 170 b (FIGS. 1A-3) and their corresponding materials,elements, and components.

In particular, in some embodiments, the flame control electrodes 200 cmay be secured to or mounted on the chamber wall 150 c in any number ofsuitable ways, which may at least temporarily attach the flame controlelectrodes 200 c to the chamber wall 150 c. For example, the flamecontrol electrodes 200 c may be attached to the chamber wall 150 c withan adhesive, by wrapping portions of the flame control electrodes 200 cabout one or more post on the chamber wall 150 c (e.g., around screws,nails, etc.), among others. Subsequently, at least partially moltenglass may be pressed against the chamber wall 150 c and the flamecontrol electrodes 200 c to form the insulation element 210 c about theflame control electrodes 200 c. Furthermore, in some instances, theinsulation element 210 c may secure the flame control electrodes 200 cto the chamber wall 150 c.

Alternatively, however, the flame control electrodes 200 c may bepositioned at least partially inside or embedded within the insulationelement 210 c, while the material of the insulation element 210 c may bein a softened state (e.g., partially molten). Thereafter, the insulationelement 210 c may be pressed against and/or adhered to the chamber wall150 c. Also as mentioned above, the flame control electrode assembly 170c may be fastened or otherwise secured to the chamber wall 150 c. Forinstance, the insulation element 210 c may assume its hardened or finalstate before the flame control electrode assembly 170 c is mounted onthe chamber wall 150 c.

Moreover, embodiments of the invention are not limited insulationelements that include glass. Accordingly, for example, insulationelements, such as the insulation element 210 c, may include any numberof suitable materials that may be secured to the chamber wall 150 c.Likewise, suitable materials for the insulation elements also may allowplacement of the flame control electrodes 200 c at least partiallyinside the insulation element 210 c before mounting the insulationelement 210 c to the chamber walls 150.

While in some embodiments flame control electrodes of the flame controlelectrode assembly may be positioned inside a single insulation element,in additional or alternative embodiments, at least some of the flamecontrol electrodes may be at least partially wrapped and/or encapsulatedin an electrically insulating material. FIG. 5, for example, illustratesa flame control electrode assembly 170 d that include individuallyinsulated flame control electrodes 200 d. Except as otherwise describedherein, the flame control electrode assembly 170 d and its materials,elements, and components may be similar to or the same as any of theflame control electrode assemblies 170, 170 a, 170 b, 170 c (FIGS. 1A-4)and their corresponding materials, elements, and components.

For example, the flame control electrodes 200 d may have anapproximately circular cross-section and may be encapsulated ininsulation elements 210 d that have at least a partially circularcross-section (e.g., insulation elements 210 d may form insulation,which has at least a portion that has approximately uniform thickness).Moreover, the insulation elements 210 d may be at least partiallyflattened or molten, such as at a base thereof, in a manner that mayattach the insulation elements 210 d to the chamber wall 150 d.Consequently, in some embodiments, each of the flame control electrodes200 d (and the insulation elements 210 d) may be attached to the chamberwall 150 d independently of other flame control electrodes 200 d. Suchconfiguration may facilitate scaling of the combustion system.Additionally or alternatively, such configuration may facilitate removaland/or replacement of the flame control electrodes 200 d (e.g.,replacement damaged flame control electrodes 200 d, removal ofunnecessary flame control electrodes 200 d, etc.).

Also, in some embodiments, the insulation elements 210 d may have hollowshapes or tubular configuration. For example, the insulation elements210 d may be extruded to form the tubular shapes thereof. In any event,in an embodiment, the flame control electrodes 200 d may be insertedinto and/or secured within the insulation elements 210 d. In someinstances, the electrodes 200 d may be first inserted into theinsulation elements 210 d and subsequently, the insulation elements 210d together with the flame control electrodes 200 d may be mounted on thechamber wall 150 d. Alternatively, the insulation elements 210 d may befirst mounted on the chamber wall 150 d, and subsequently, the flamecontrol electrodes 200 d may be inserted into and/or secured within theinsulation elements 210 d.

Furthermore, as described above, the flame control electrodes of theflame control electrode assembly may have any number of suitablecross-sectional shapes. Generally, in one or more embodiments, the flamecontrol electrodes may be elongated and/or wire-like members, which mayextend along one or more chamber walls. In some embodiments, as shown inFIG. 6, the flame control electrodes may have an approximatelyrectangular cross-section. More specifically, FIG. 6 illustrates a flamecontrol electrode assembly 170 e that includes flame control electrodes200 e mounted on the chamber wall 150 e. Except as otherwise describedherein, the flame control electrode assembly 170 e and its materials,elements, and components may be similar to or the same as any of theflame control electrode assemblies 170, 170 a, 170 b, 170 c, 170 d(FIGS. 1A-5) and their corresponding materials, elements, andcomponents.

In some examples, the flame control electrodes 200 e may have noinsulation or may have a thin insulating coating thereon. For instance,the flame control electrodes 200 e may be spaced apart in a manner thatprevents or minimize occurrences of shorting therebetween (e.g., whichmay be caused by the charged particles in the flame). In any event, someembodiments may include uninsulated flame control electrodes 200 e.Moreover, in at least one embodiment, the uninsulated flame controlelectrodes 200 e may provide increased heat transfer from the flame (ascompared with the insulated flame control electrodes).

As noted above, the cross-sectional shape of the flame controlelectrodes may vary from one embodiment to the next. Likewise, thecross-sectional shape of the insulation placed about the flame controlelectrodes may vary from one embodiment to another. Similarly,cross-sectional shapes of the insulation may vary from one embodiment toanother. In an embodiment, as shown in FIG. 7, a flame control electrodeassembly 170 f may include flame control electrodes 200 fencased/encapsulated in insulation elements 210 f, 210 g. Except asotherwise described herein, the flame control electrode assembly 170 fand its materials, elements, and components may be similar to or thesame as any of the flame control electrode assemblies 170, 170 a, 170 b,170 c, 170 d, 170 e (FIGS. 1A-6) and their corresponding materials,elements, and components. For example, the flame control electrodeassembly 170 f may be mounted or secured to the chamber wall 150 f inthe same or similar manner as described above.

In some embodiments, the insulation elements 210 g and/or 210 f may beat least partially melted or softened in a manner that may bond theinsulation elements 210 g and/or 210 f to the chamber wall 150 f,thereby securing the flame control electrodes 200 f to the chamber wall150 f Also, the insulation elements 210 f and 210 g may be bonded to oneanother, thereby forming substantially uniform insulation elements 210fg. Moreover, as mentioned above, the insulation elements 210 fg formedby the insulation elements 210 f and 210 g may have different shapes(e.g., different cross-sectional shapes) than the flame controlelectrodes 200 f. In the illustrated example, the insulation elements210 fg have approximately square cross-sectional shapes, while the flamecontrol electrodes 200 f have approximately circular cross-sectionalshapes. It should be appreciated, however, that the flame controlelectrodes and the insulation elements may have any suitablecross-sectional shape (e.g., circular, rectangular, oval, irregular,etc.), which may vary from one embodiment to the next.

Embodiments of the invention also may include a method reducing NOxproduced by any of the combustion systems disclosed herein. For example,as illustrated in FIG. 8, the method may include an act 310 of arrangingat least one flame control electrode assembly inside a combustionchamber. In particular, embodiments may involve securing at least oneflame control electrode assembly to one or more walls of the combustionchamber. As described above, the flame control electrode assembly may beoperably connected to a controller that may control operation of theflame control electrodes. In some instance, the controller mayadditionally or alternatively control operation of one or more ionizers,which may charge the fuel, oxidizer, flame, or combinations thereof.

The method also may include an act 320 of biasing the flame controlelectrodes to generate an electric field. For instance, the controllermay apply a voltage to the flame control electrodes in a manner thatproduces an electric field near the chamber wall. The controller alsomay vary the voltage to adjust the electric field based on combustion offuel (e.g., based on the amount of fuel and/or oxidizer injected intothe combustion chamber, flame temperature, etc.).

Moreover, the method may include an act 330 of attracting a flame to oneor more chamber walls of the combustion chamber. In some embodiment, theflame may be attracted to the chamber walls or portions thereof locatedbetween the fuel nozzle(s) and the flue. In any case, in an embodiment,the controller may apply sufficient voltage to flame control electrodeassembly to produce a suitable electric field that may attract the flameto the chamber walls.

For example, as mentioned above, the flame may have a net positive ornegative charge, which may result from ionizing the fuel and/or theoxidizer. In alternative or additional embodiments, ions may be injecteddirectly into the flame to produce a net charge. Hence, in at least oneembodiment, the flame may have a net charge, and the flame controlelectrode assembly and controller may produce an oppositely chargedelectric field that may be located near one or more chamber walls. Assuch, the flame control electrode assembly may attract the flame to oneor more chamber walls.

When the flame is attracted to the chambers walls, heat from the flamemay be transferred to the chamber walls, thereby reducing combustiontemperature of the flame. In some instances, reducing combustiontemperature of the flame may reduce NOx produced during combustion.Accordingly, in some embodiments, the method includes an act 340 ofdissipating heat from the flame to reduce NOx. It should be appreciatedthat heat transferred from the flame to chamber walls may be furtherdissipated from the walls (e.g., to environment outside of thecombustion chamber and/or to one or more elements or components intendedto be heated).

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges that come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. A combustion system, comprising: a combustion chamber including atleast one chamber wall; a source of combustible fuel for producing aflame in the combustion chamber; and a flame control electrode assemblymounted to the at least one chamber wall, the flame control electrodeassembly including a plurality of flame control electrodes, the flamecontrol electrode assembly being configured to produce an electric fieldand attract the flame toward the at least one chamber wall.
 2. Thesystem of claim 1, further comprising a controller electrically coupledto the flame control electrode assembly, the controller being configuredto regulate the electric field produced by the flame control electrodeassembly.
 3. The system of claim 3, wherein the controller is configuredto regulate the electric field produced by the flame control electrodeassembly at least in part based on the net charge of the flame.
 4. Thesystem of claim 1, wherein one or more of the plurality of flame controlelectrodes is at least partially enclosed by one or more insulationelements.
 5. The system of claim 4, wherein the one or more insulationelements include a plurality of insulation elements, and at least one ofthe plurality of flame control electrodes is encapsulated betweenmultiple insulation elements bonded together.
 6. The system of claim 4,wherein at least one of the one or more insulation elements has atubular shape, and at least one of the plurality of flame controlelectrodes is located within a hollow space of the tubular shape.
 7. Thesystem of claim 4, wherein at least one of the one or more insulationelements is secured to the at least one chamber wall.
 8. The system ofclaim 4, wherein the one or more insulation elements have sheet-likeshapes and at least some of the flame control electrodes are locatedbetween the sheet-like shaped insulation elements that are bondedtogether.
 9. The system of claim 4, wherein the flame control electrodesare embedded within at least one of the one or more insulation elements.10. The system of claim 4, wherein the plurality of flame controlelectrodes include a refractory material and the one or more insulationelements include electrically insulating material.
 11. The system ofclaim 1, further comprising one or more heat exchangers configured totransfer heat from the combustion chamber.
 12. A method of reducing NOxproduced during combustion in a combustion chamber, the methodcomprising: combusting a fuel inside of the combustion chamber toproduce a flame having a net positive charge or net negative charge;producing an electric field having a charge opposite to the flamecharge, the electric field being positioned near at least one chamberwall of the combustion chamber; attracting the flame toward the at leastone chamber wall; and transferring heat from the flame to the at leastone chamber wall to thereby reduce a combustion temperature of theflame.
 13. The method of claim 12, wherein producing an electric fieldhaving a charge opposite to the flame charge includes biasing a flamecontrol electrode assembly positioned near the at least one chamberwall.
 14. The method of claim 13, wherein producing an electric fieldhaving a charge opposite to the flame charge includes determining thenet charge of the flame.
 15. The method of claim 13, further comprisingat least partially electrically insulating a plurality of flame controlelectrodes of the flame control electrode assembly by one or moreinsulating elements.
 16. The method of claim 15, wherein at least one ofthe flame control electrodes is embedded within the one or moreinsulating elements.
 17. The method of claim 13, wherein transferringheat from the flame includes transferring heat to one or more of the atleast one chamber wall or the flame control electrode assembly.
 18. Themethod of claim 17, further comprising transferring heat from one ormore of the at least one chamber wall or the flame control electrodeassembly to a first heat exchanger.
 19. The method of claim 12, whereincombusting a fuel inside of the combustion chamber to produce a flamehaving a net positive charge or net negative charge includes injectingpositively or negatively charged particles into one or more of the fuel,an oxidizer, or the flame.
 20. A combustion system, comprising: acombustion chamber including at least one chamber wall; a source ofcombustible fuel for producing a flame in the combustion chamber; atleast one ionizer positioned and configured to ionize one or more of thefuel, combustion air, or the produced flame; a flame control electrodeassembly mounted to the at least one chamber wall, the flame controlelectrode assembly including a plurality of flame control electrodesthat are electrically insulated from each other, the flame controlelectrode assembly being configured to produce an electric field thatattracts the flame toward the at least one chamber wall; and acontroller electrically coupled to the flame control electrode assembly,the controller being configured to regulate the electric field producedby the flame control electrode assembly.